This section provides background information related to the present disclosure which is not necessarily prior art.
Vehicles are known to incorporate HVAC systems to improve the comfort of the people within the passenger compartment of the vehicle. The HVAC systems heat and cool air blown through the HVAC system using a heating heat exchanger and/or a cooling heat exchanger. The heating heat exchanger typically utilizes the engine coolant as a source of heat for heating the air. The cooling heat exchanger is typically an evaporator which is part of an air conditioning system in the vehicle powered by the engine of the vehicle. The air blown through the HVAC system comes from air outside the vehicle, air inside the passenger compartment of the vehicle or a combination of the air outside the vehicle and the air inside the passenger compartment of the vehicle. The air being blown through the HVAC system is conditioned (heated/cooled) and is then directed into the passenger compartment of the vehicle through one or more outlet vents.
Although these vehicle HVAC systems have worked for their intended purposes, some disadvantages remain. For instance, these HVAC systems typically include an exterior air intake vent through which air from outside the vehicle enters the HVAC system (fresh mode). These HVAC systems also typically include an interior air intake vent through which air from inside the vehicle enters the HVAC system (recirculation mode). In a mixture configuration where air from the exterior air intake vent and air from the interior air intake vent are mixed (partial recirculation mode), both the exterior air intake vent and the interior air intake vent are open.
One disadvantage of the typical air intake systems of the present day is the packaging size required for the dual intake system for air from outside the vehicle and air from inside the vehicle. In addition, these present day systems only allow for three specific control or intake modes. These three modes are a fresh mode where only air from outside the vehicle is used, a partial recirculation mode where both air from outside the vehicle and air from inside the vehicle is used and a recirculation mode where only air from inside the vehicle is used. Another disadvantage to a system that only includes the three modes listed above is a loss of potential performance during vehicle warm up because you must pull all airflow from the fresh mode during the vehicle warm up to avoid window fogging or risk an air leak from outside the vehicle (fresh mode) directly to the inside of the vehicle because of no partial door seal. If a dedicated partial mode is provided, you can use a combination of both the recirculation mode and the fresh mode which is more efficient because the inside air is already warmer than the outside air.